As one sharpens a knife on a whetstone, the brain can be sharpened on dull objects of thought. Every form of assiduous thinking has its value.
There is no such whetstone, to sharpen a good wit and encourage a will to learning, as is praise.Roger Ascham
In going where you have to go, and doing what you have to do, and seeing what you have to see, you dull and blunt the instrument you write with. But I would rather have it bent and dulled and know I had to put it on the grindstone again and hammer it into shape and put a whetstone to it, and know that I had something to write about, than to have it bright and shining and nothing to say, or smooth and well oiled in the closet, but unused.ernest hemingway